Make ModRefBehavior a lattice. Use this to clean up AliasAnalysis
chaining and simplify FunctionAttrs' GetModRefBehavior logic.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118660 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 73114fe..bf1b689 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -595,7 +595,7 @@
Min = OnlyReadsMemory;
// The AliasAnalysis base class has some smarts, lets use them.
- return std::min(AliasAnalysis::getModRefBehavior(CS), Min);
+ return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
}
/// getModRefBehavior - Return the behavior when calling the given function.
@@ -613,12 +613,14 @@
#undef GET_INTRINSIC_MODREF_BEHAVIOR
}
+ ModRefBehavior Min = UnknownModRefBehavior;
+
// If the function declares it only reads memory, go with that.
if (F->onlyReadsMemory())
- return OnlyReadsMemory;
+ Min = OnlyReadsMemory;
// Otherwise be conservative.
- return AliasAnalysis::getModRefBehavior(F);
+ return ModRefBehavior(AliasAnalysis::getModRefBehavior(F) & Min);
}
/// getModRefInfo - Check to see if the specified callsite can clobber the
@@ -671,6 +673,8 @@
return NoModRef;
}
+ ModRefResult Min = ModRef;
+
// Finally, handle specific knowledge of intrinsics.
const IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction());
if (II != 0)
@@ -686,7 +690,7 @@
if (isNoAlias(Location(Dest, Len), Loc)) {
if (isNoAlias(Location(Src, Len), Loc))
return NoModRef;
- return Ref;
+ Min = Ref;
}
break;
}
@@ -745,7 +749,7 @@
}
// The AliasAnalysis base class has some smarts, lets use them.
- return AliasAnalysis::getModRefInfo(CS, Loc);
+ return ModRefResult(AliasAnalysis::getModRefInfo(CS, Loc) & Min);
}
/// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction